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                <ol class="chapter"><li class="chapter-item expanded affix "><a href="../../index.html">Introduction</a></li><li class="chapter-item expanded "><a href="../../01-background/index.html"><strong aria-hidden="true">1.</strong> Background</a></li><li class="chapter-item expanded "><a href="../../02-requirements/index.html"><strong aria-hidden="true">2.</strong> Hardware/knowledge requirements</a></li><li class="chapter-item expanded "><a href="../../03-setup/index.html"><strong aria-hidden="true">3.</strong> Setting up a development environment</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../03-setup/linux.html"><strong aria-hidden="true">3.1.</strong> Linux</a></li><li class="chapter-item expanded "><a href="../../03-setup/windows.html"><strong aria-hidden="true">3.2.</strong> Windows</a></li><li class="chapter-item expanded "><a href="../../03-setup/macos.html"><strong aria-hidden="true">3.3.</strong> macOS</a></li><li class="chapter-item expanded "><a href="../../03-setup/verify.html"><strong aria-hidden="true">3.4.</strong> Verify the installation</a></li></ol></li><li class="chapter-item expanded "><a href="../../04-meet-your-hardware/index.html"><strong aria-hidden="true">4.</strong> Meet your hardware</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../04-meet-your-hardware/microbit-v2.html"><strong aria-hidden="true">4.1.</strong> micro:bit v2</a></li><li class="chapter-item expanded "><a href="../../04-meet-your-hardware/microbit-v1.html"><strong aria-hidden="true">4.2.</strong> micro:bit v1</a></li><li class="chapter-item expanded "><a href="../../04-meet-your-hardware/terminology.html"><strong aria-hidden="true">4.3.</strong> Rust Embedded terminology</a></li></ol></li><li class="chapter-item expanded "><a href="../../05-led-roulette/index.html"><strong aria-hidden="true">5.</strong> LED roulette</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../05-led-roulette/build-it.html"><strong aria-hidden="true">5.1.</strong> Build it</a></li><li class="chapter-item expanded "><a href="../../05-led-roulette/flash-it.html"><strong aria-hidden="true">5.2.</strong> Flash it</a></li><li class="chapter-item expanded "><a href="../../05-led-roulette/debug-it.html"><strong aria-hidden="true">5.3.</strong> Debug it</a></li><li class="chapter-item expanded "><a href="../../05-led-roulette/light-it-up.html"><strong aria-hidden="true">5.4.</strong> Light it up</a></li><li class="chapter-item expanded "><a href="../../05-led-roulette/it-blinks.html"><strong aria-hidden="true">5.5.</strong> It blinks</a></li><li class="chapter-item expanded "><a href="../../05-led-roulette/the-challenge.html"><strong aria-hidden="true">5.6.</strong> The challenge</a></li><li class="chapter-item expanded "><a href="../../05-led-roulette/my-solution.html"><strong aria-hidden="true">5.7.</strong> My solution</a></li></ol></li><li class="chapter-item expanded "><a href="../../06-serial-communication/index.html"><strong aria-hidden="true">6.</strong> Serial communication</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../06-serial-communication/nix-tooling.html"><strong aria-hidden="true">6.1.</strong> *nix tooling</a></li><li class="chapter-item expanded "><a href="../../06-serial-communication/windows-tooling.html"><strong aria-hidden="true">6.2.</strong> Windows tooling</a></li></ol></li><li class="chapter-item expanded "><a href="../../07-uart/index.html"><strong aria-hidden="true">7.</strong> UART</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../07-uart/send-a-single-byte.html"><strong aria-hidden="true">7.1.</strong> Send a single byte</a></li><li class="chapter-item expanded "><a href="../../07-uart/send-a-string.html"><strong aria-hidden="true">7.2.</strong> Send a string</a></li><li class="chapter-item expanded "><a href="../../07-uart/naive-approch-write.html"><strong aria-hidden="true">7.3.</strong> Naive approach and write!</a></li><li class="chapter-item expanded "><a href="../../07-uart/receive-a-single-byte.html"><strong aria-hidden="true">7.4.</strong> Receive a single byte</a></li><li class="chapter-item expanded "><a href="../../07-uart/echo-server.html"><strong aria-hidden="true">7.5.</strong> Echo server</a></li><li class="chapter-item expanded "><a href="../../07-uart/reverse-a-string.html"><strong aria-hidden="true">7.6.</strong> Reverse a string</a></li><li class="chapter-item expanded "><a href="../../07-uart/my-solution.html"><strong aria-hidden="true">7.7.</strong> My solution</a></li></ol></li><li class="chapter-item expanded "><a href="../../08-i2c/index.html"><strong aria-hidden="true">8.</strong> I2C</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../08-i2c/the-general-protocol.html"><strong aria-hidden="true">8.1.</strong> The general protocol</a></li><li class="chapter-item expanded "><a href="../../08-i2c/lsm303agr.html"><strong aria-hidden="true">8.2.</strong> LSM303AGR</a></li><li class="chapter-item expanded "><a href="../../08-i2c/read-a-single-register.html"><strong aria-hidden="true">8.3.</strong> Read a single register</a></li><li class="chapter-item expanded "><a href="../../08-i2c/using-a-driver.html"><strong aria-hidden="true">8.4.</strong> Using a driver</a></li><li class="chapter-item expanded "><a href="../../08-i2c/the-challenge.html"><strong aria-hidden="true">8.5.</strong> The challenge</a></li><li class="chapter-item expanded "><a href="../../08-i2c/my-solution.html"><strong aria-hidden="true">8.6.</strong> My solution</a></li></ol></li><li class="chapter-item expanded "><a href="../../09-led-compass/index.html"><strong aria-hidden="true">9.</strong> LED compass</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../09-led-compass/calibration.html"><strong aria-hidden="true">9.1.</strong> Calibration</a></li><li class="chapter-item expanded "><a href="../../09-led-compass/take-1.html"><strong aria-hidden="true">9.2.</strong> Take 1</a></li><li class="chapter-item expanded "><a href="../../09-led-compass/solution-1.html"><strong aria-hidden="true">9.3.</strong> Solution 1</a></li><li class="chapter-item expanded "><a href="../../09-led-compass/take-2.html"><strong aria-hidden="true">9.4.</strong> Take 2</a></li><li class="chapter-item expanded "><a href="../../09-led-compass/solution-2.html"><strong aria-hidden="true">9.5.</strong> Solution 2</a></li><li class="chapter-item expanded "><a href="../../09-led-compass/magnitude.html"><strong aria-hidden="true">9.6.</strong> Magnitude</a></li></ol></li><li class="chapter-item expanded "><a href="../../10-punch-o-meter/index.html"><strong aria-hidden="true">10.</strong> Punch-o-meter</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../10-punch-o-meter/gravity-is-up.html"><strong aria-hidden="true">10.1.</strong> Gravity is up?</a></li><li class="chapter-item expanded "><a href="../../10-punch-o-meter/the-challenge.html"><strong aria-hidden="true">10.2.</strong> The challenge</a></li><li class="chapter-item expanded "><a href="../../10-punch-o-meter/my-solution.html"><strong aria-hidden="true">10.3.</strong> My solution</a></li></ol></li><li class="chapter-item expanded "><a href="../../explore.html"><strong aria-hidden="true">11.</strong> What's left for you to explore</a></li><li class="spacer"></li><li class="chapter-item expanded affix "><a href="../../appendix/1-general-troubleshooting/index.html" class="active">General troubleshooting</a></li><li class="chapter-item expanded affix "><a href="../../appendix/2-how-to-use-gdb/index.html">How to use GDB</a></li><li class="spacer"></li></ol>
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                    <h1 class="menu-title">Discovery</h1>

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                        <h1 id="general-troubleshooting"><a class="header" href="#general-troubleshooting">General troubleshooting</a></h1>
<h2 id="cargo-embed-problems"><a class="header" href="#cargo-embed-problems"><code>cargo-embed</code> problems</a></h2>
<p>Most <code>cargo-embed</code> problems are either related to not having installed the <code>udev</code>
rules properly (on Linux) or having selected the wrong chip configuration in <code>Embed.toml</code> so
make sure you got both of those right.</p>
<p>If the above does not work out for you, you can open an issue in the <a href="https://github.com/rust-embedded/discovery/issues"><code>discovery</code> issue tracker</a>.
Alternatively you can also visit the <a href="https://matrix.to/#/#rust-embedded:matrix.org">Rust Embedded matrix channel</a> or the <a href="https://matrix.to/#/#probe-rs:matrix.org">probe-rs matrix channel</a>
and ask for help there.</p>
<h2 id="cargo-problems"><a class="header" href="#cargo-problems">Cargo problems</a></h2>
<h3 id="cant-find-crate-for-core"><a class="header" href="#cant-find-crate-for-core">&quot;can't find crate for <code>core</code>&quot;</a></h3>
<h4 id="symptoms"><a class="header" href="#symptoms">Symptoms</a></h4>
<pre><code>   Compiling volatile-register v0.1.2
   Compiling rlibc v1.0.0
   Compiling r0 v0.1.0
error[E0463]: can't find crate for `core`

error: aborting due to previous error

error[E0463]: can't find crate for `core`

error: aborting due to previous error

error[E0463]: can't find crate for `core`

error: aborting due to previous error

Build failed, waiting for other jobs to finish...
Build failed, waiting for other jobs to finish...
error: Could not compile `r0`.

To learn more, run the command again with --verbose.
</code></pre>
<h4 id="cause"><a class="header" href="#cause">Cause</a></h4>
<p>You forgot to install the proper target for your microcontroller (<code>thumbv7em-none-eabihf</code> for v2
and <code>thumbv6m-none-eabi</code> for v1).</p>
<h4 id="fix"><a class="header" href="#fix">Fix</a></h4>
<p>Install the proper target.</p>
<pre><code class="language-console"># micro:bit v2
$ rustup target add thumbv7em-none-eabihf

# micro:bit v1
$ rustup target add thumbv6m-none-eabi
</code></pre>

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